Speech Perception by Non-Native Speakers Declines Drastically in Noisy Conditions

1. Speech Perception by Non-Native Speakers Declines Drastically in Noisy Conditions Catherine Caldwell-Harris, Inna Ryvkin, Andrei Anghelescu, Loraine K. Obler Catherine Caldwell-Harris Boston University

2. Expert language processing system cleans up noisy input -- Wow! Highly fluent speakers • Fill in from meaning • Are more sensitive to auditory cues (Barbara Shinn-Cunninghams’ talk) Catherine Caldwell-Harris Boston University

3. We already know a lot about factors influencing non-native speech perception ‘Fluency/ability’ matters; and these factors influence fluency(in order of strength): • Proficiency • Number of years of language use • Amount and type of current use • Age of acquisition (often determines above factors) Task and input factors • Noise / environment • Sentence context (predictability of words) Catherine Caldwell-Harris Boston University

4. But much less is known about: How factors that influence skill level interact • Is early acquisition important even controlling for proficiency and current use? Does word frequency matter? How do input factors interact? • Examine word freq in high/low predictable context Similarity between first and second language • Those great Dutch learners of English! Catherine Caldwell-Harris Boston University

5. Speech Perception In Noise Test (Bilger, 1984) Participants were instructed to repeat the last word of each sentence. 80 items selected from the original SPIN sentences. Three variables, fully crossed: • predictability of target (Predictable/Unpredictable) • lexical frequency of target (High/Low) • noise (Noise/Clear). The noise consisted of multi-speaker babble. • Signal-to-noise ratio was -2dB for sentence-plus-noise items. • Each item is a sentence that was prerecorded by an adult male and presented in stereo through headphones. Clear, predictable Noise, predictable Clear, unpredictable Noise unpredictable Catherine Caldwell-Harris Boston University

6. Examples of conditions Predictable Context Target His plan meant taking a big risk. Hi Freq Tom fell down and got a bad bruise. Lo Freq Unpredictable Context Bill might discuss the foam. Hi Freq I was considering the crook. Lo Freq Catherine Caldwell-Harris Boston University

7. Questions in Current Study Similarity between first and second language • With L1 Spanish, Russian, Mandarin When identifying targets in spoken English • Predict: Spanish > Russian > Mandarin High/low frequency of target words • Predict: frequency effects will depend on proficiency Age of acquisition • Predict: Doesn’t matter, after controlling for proficiency? Catherine Caldwell-Harris Boston University

8. Procedure • Questionnaire • Language History • Self-rating of proficiency in L1 and English • Adult English Language Use Scale (AELU) • Hearing Threshold determination • SPIN meant to be administered 50dB above hearing threshold. • Threshold tested via a Behringer UB502 Eurorack 5 Input Mixer Catherine Caldwell-Harris Boston University

9. Learning History Variables

13. Overview of Results • Native English-speakers performed nearly at ceiling, Mandarin speakers performed most poorly, and Spanish- and Russian-speakers show in intermediate results. • Noise, predictability, frequency matter for all speakers • BUT: Lexical frequency of target is a small effect of native English speakers Catherine Caldwell-Harris Boston University

14. Effect sizes for main effects and interactions Catherine Caldwell-Harris Boston University

16. Predictable Hi Freq Unpredictable Hi Freq Predictable Lo Freq Unpredictable Lo Freq

17. Spanish L1

18. Russian L1

19. Mandarin L1

20. Need more participants to determine cline of Spanish > Russian > Mandarin Statistically, group differences greatly diminished when ages-of-arrival are taken into account. Age-of-arrival effects very strong. Why? Age-of-arrival may organize immigrants’ language learning environment (Caldwell-Harris et al, under review). Still,plots for language groups show steeper slope for decline in target word detection with age-of-arrival for Mandarin speakers. But Mandarin group had on average later age-of-arrival. Catherine Caldwell-Harris Boston University

21. Learning History Variables

22. Answers in Current Study Similarity between first and second language • Comparing L1 Spanish, Russian, Mandarin • Confirmed: Spanish > Russian > Mandarin • But: age-of-arrival confound High/low frequency of target words • Confirmed: frequency effects depend on proficiency • Implies ‘subject/experienced’ proficiency is what matters for processing. For high proficiency speakers, need very low freq words? Is log transform sufficient? Catherine Caldwell-Harris Boston University

23. Second language learning ideal for neural net modeling Use modeling to clarify proposals about main effects and interactions of: • The role of frequency (why frequency effects disappear for high proficiency learners) • Predictability -- test hypotheses about when lower proficiency learners can use context to make predictions • Vary L1-L2 similarity in simulations • Vary “age of exposure” and intensity of language contact Catherine Caldwell-Harris Boston University